Valve arrangement for the working cylinder of a pneumatically operated stapler

ABSTRACT

A valve arrangement of a pneumatically operated stapler comprising one or a plurality of annular valve chambers with one or a plurality of elastic, radially deformable rings. An additional elastic, radially deformable ring or gasket is mounted underneath the working cylinder. The outer rim of which gasket communicates via a channel with an adjoining chamber of the working cylinder and the inner rim serves as a closing member for the outlet opening of the working cylinder.

United States Patent 11 1 Lange 1 1 Aug. 26, 1975 [54] VALVE ARRANGEMENTFOR THE 3,392,632 7/1968 Volkman v 91/457 WORKING CYLINDER OF A3,396,636 8/1968 Bade 91/399 3.680582 8/1972 Pauliukonis. 25l/DIG. lPNEUMATKALLY OPERATED STAPLER 3.715.069 2/1973 OConncr 227/130 [75]Inventor: Wilfried Lange, Altenhngem 3,788,195 l/l974 Langc 227/130 XGermany [73] Assignee: Bukama Gmbl-l Hannover, Primary Examiner-Irwin C.Cohen Hemmingen-Westcrfeld Germany Attorney, Agent, or Firm-Allison C.Collard [22] Filed: Oct. 25, 1973 [21] Appl. No: 409,564 [57] ABSTRACT Avalve arrangement of a pneumatically operated stal l Forelgn ApplicationPnorlty Data pler comprising one or a plurality of annular valve Oct 27,1972 Germany 2252735 chambers with one or a plurality of elastic,radially deformable rings. An additional elastic, radially deform- [52]U.S. Cl. 91/461; 91/399; 227/130 able ring or gasket is mountedunderneath the working [51 Int. Cl.'- F15B 11/08; FlSB 13/042 cylinder.The outer rim of which gasket communicates [58] Field of Search 91/399,23, 402, 367, 461, via-a channel with an adjoining chamber of the work-91/304; 227/130 ing cylinder and the inner rim serves as a closingmember for the outlet opening of the working cylin- [56] ReferencesCited der;

UNITED STATES PATENTS 3 Cl 4 D F 3,304,872 2/1967 English 137/525 xrawmg gums All PATENIED mczsms sum 1 OF 4 sum 3 0F 9 [III/II Mil? A ENEIII/14mm 2 27 i IM VALVE ARRANGEMENT FOR THE WORKING CYLINDER OF APNEUMATICALLY OPERATED STAPLER This invention relates to a valvearrangement for the working cylinder of a pneumatically operated stapleror other percussion machine. particularly of a stapler controlled by anauxiliary valve having in its compressed air conducting channel one or aplurality of annular valve chambers provided with one or severalflexible rings deformable in radial direction. the outer rims of whichrings constitute control pressure areas that are subject to be affectedby the auxiliary valve and the inner rims of which constitute closingmembers for the compressed air channel.

For venting the backstroke or return motion chamber of the workingcylinder of a pneumatically operated stapler it was customary heretoforeto use both spring-loaded valves and slide members. In one of the priorart outlet a valve arrangement according to the US. Pat. No. 3.396.636 acylindrical passage opening of an annular elastic buffer mounted at thebottom of the working cylinder is provided with a springloaded return orcheck valve which is being held open by its biased spring during thestroke of the working piston and which ventilates the backstroke space.The working piston in its lower dead center position strikes the bufferand seals off. in this connectiornits passage opening. Simultaneouslycompressed air passes from the adjoining chamber through the radialbores of the working cylinder into the backstroke chamber at itsinferior or foot side and actuates the check valve for closing purposeswhereby the air from the adjoining chamher is being sealed off againstthe ambient air and the working piston returns to its initial position.The check valve is controlled in this connection essentially in amechanical manner by way of the stroke ofthe working piston. subjectingit to extensive mechanical wear and tear.

A slide valve gear or control of the aforementioned type has beendisclosed by way of the German Pat. Specification No. 1.997.069. Saidcontrol means oper ates on the outlet opening of the backstroke chamberof the working cylinder.

By means of a slide control of this type the outlet opening of theworking cylinder is no longer controlled by the mechanical strokeexerted when the working cylinder is in its lower dead center position,rather the control is performed completely pneumatically so as toprovide for longer durability than can be had by the use of aspring-loaded check valve. For tools operating at a high stroke rate andwhich require. therefore, very short switching times slide valvecontrols can be employed to advantage only within a very restrictedrange of application. The inertia forces alone set limits to the use ofslides for the control of the outlet openings in tools having a highstroke rate. Additionally. slide controls or gears are not capable ofmaking on the spot available for cross sections for attaining the highstroke rate. as is often required. Due to this fact also. the realm ofapplication for slides is further restricted.

' It is an aim or object of this invention to provide the valvearrangement for the outlet opening of the backstroke chamber of theworking cylinder for tools of the aforementioned type in a manner suchthat large cross sections can be cleared instantaneously and extremelyshort switching times may be obtained.

This aim and object of the invention is attained according to theinvention by the arrangement of an additional elastic. radiallydeformable ring in an annular groove of the tool housing underneath theworking cylinder. the outer rim of said ring forming a control pressurearea and its inner rim serving as closing or shut-off member for theoutlet opening of the working cylinder. The outer rim of the elasticring may both be connected via a channel to an adjoining chamber of theworking cylinder and. also. via a channel followed by a tube. as thecase may be. to the housing bore of the auxiliary valve for the controlof the compressed air supply into the working chamber of the workingcylinder. It is of particular advantage to arrange a throttle in thechannel leading to the outer rim of the elastic ring so as to delay theworking medium flowing therein.

According to the invention. the interposition of the elastic ring. e.g.in the form of an O-ring provides for clearing a large cross section. soas to allow the working medium located during the working strokeunderneath the working piston to be discharged immediately. An elasticring of this type has but little mass. which is essential for obtainingvery short switching times. Moreover. it is to be observed that themovement of a control member of this type is not effected in thedirection of motion of the working cylinder but radially and. hence.symmetrically to the direction of motion of the piston. Vibration orverberation and the concomitant slight motion of the tool is thereforeentirely obviated.

The invention will now be described by way of example with reference tothe attached drawings. in which:

FIG. 1 is longitudinal section through the working cylinder and thehousing of the stapler enclosing said working cylinder. with the workingcylinder in its initial or starting position;

FIG. 2 is a longitudinal section according to FIG. I with the releaselever in its retracted position and the working cylinder at the momentof striking the impact buffer;

FIG. 3 shows the same operational position as FIG. 2. the gasket howeverin a different position after the stroke imparted by the workingcylinder to the impact buffer. and

FIG. 4 illustrates the connection of the gasket to the control channelof the intake valve.

The pneumatically operated stapler is provided with a handle-typehousing I enclosing an compressed air reservoir 2 connected to acompressed air conduit and containing in its forward portion 3 a workingcylinder 4 wherein a piston 5 is mounted for reciprocating movement. Thepiston 5 is provided at its lower surface with a prolongation 6 to whicha driving blade or ram 7 is connected penetrating the cylinder bottom 9which carries an elastic. annular buffer 8 and which ram 7 drives.during its working stroke. a staple. nail or the like from a magazine 10into a workpiece (not shown The compressed air reservoir 2 encloses theupper portion of the working cylinder 4 the lower part of which maypossibly be surrounded by an adjoining chamber closed off by way of anintermediary wall II. and communicating therewith by means of passages13 and 14.

The upper end of the working cylinder 4 forms to-. gcther with the upperhousing portion 15 an annular channel 16 which communicates via afunnel-shaped groove 17 with the reservoir 2. An annular valve chamber18 is arranged in the inner wall of the housing.

which wall defines said annular channel 16. Two concentric and elasticO-rings 19 are disposed in said valve chamber 18 which communicates viaa control channel 20 with the auxiliary valve 21 having its plunger 22penetrate into the compressed air reservoir 2 and mounted so as to besnugly guided in a bore 23 of the housing portion 24. The lower end ofthe plunger 22 rests on a manually operative release lever 25 mountedfor pivotal movement about a pinion 26 attached to the housing portion24. The housing bore 27 of the auxiliary valve 21 communicates via aventing channel 28 as well as via a bore 30 provided in the housingcover with the ambient air. The annular valve chamber 18 is also ventedvia a venting channel 31 and a bore 32 of the housing cover 29. Abovethe annular valve chamber 18 there is provided a turned groove 34containing an elastic Oring 33. This groove 34 communicates via achannel 35 with the housing bore 27 of the auxiliary valve 21. Theannular channel 16 surrounding the upper end of the working cylinder 4communicates via a groove 36 of the housing cover 29 with ambient air.On the housing cover 29 a protector cap 37 has been mounted whichdefines therewith a venting channel 38. A magnet 39 has been embedded onthe lower surface of the housing cover 29. This magnet 39 maintains thepiston 5 in the starting position shown in FIG. 1. In the valve plunger22 there is an axial bore 40 which connects. depending on the positionof the plunger 22, the compressed air reservoir 2 to the valve chamber18 or to the channel 33. Reference numeral 41 stands for the slot-shapedinlet openings at the upper end of the working cylinder and 42designates the interst-ices between the concentrically spaced ()-rings19.

An annular groove for receiving an elastic ring in the instant case. an()-ring 51 has been provided underneath the working cylinder 4 in thehousing 1 of the tool. According to the invention. this ()-ring 5] is toclear the passage of the working medium during the working stroke to theoutlet openings 52. A channel 53 has the annular groove 50 (FIG. 1)communicate with the adjoining chamber 12. A throttle has beeninterposed in channel 53 so as to delay the current flow. Acommunication between the elastic gasket and the control channel isillustrated in FIG. 4. The communicating conduit is a tube leading fromchannel 53 to control channel 20.

As soon as the working stroke of the piston 5 is started. i.e. as soonas it moves in downward direction. the air located below the piston inthe bakestroke chamber of the working cylinder 4 is pressed outward viaoutlet openings 52. In this connection the ring 51 is being opened dueto the pressure of air and clears the passage to the outlet openings 52.Simultaneously the working medium. which is air in this case, ispressed. however. through the openings 13 and 14 of the working cylinder4 into the adjoining chamber 12 from where pressure can be applied'viachannel 53 in conjunction with throttle 54 to the outer side of thegasket trated in FIG. 3. As soon as the release lever 25 has been freedthe plunger 22 moves again downward into its starting position wherebyboth Orings 19, as intake valves, are being compressed due to thecompressed air acting on their outer rim and the O-ring 33. is beingstretched in its starting position due to the venting of channel 35, inwhich position the annular channel 16 is opened to the ambient air sothat the piston 5 moved upward in a known manner by the compressed airfrom the adjoining chamber 12 will not experience any counteractingpressure in cylinder 4. At this moment the piston 5 begins to lift offfrom buffer 8 since the air present in the adjoining chamber 12 canattack the piston 5 from below via bores 14 of the cylinder 4 and moveit into its starting position at the upper end of the working cylinder4.

When using the connecting tube 55 the gasket or ring 51 is held in itsradially stretched position as long as the release lever 25 is drawn.This has, however, no bearing on the movement of the working piston 5since the piston blocks in its lower position the passage of the airentering via inlet slots 41 to the outlet apertures 32 due to the factthat it forms a sealing seat on buffer 8. However, as soon as therelease lever 25 is freed, the working piston 5 can return in the mannerdescribed above to its starting position; furthermore, compressed airflows via the connecting tube 35 to the outer side of the gasket 51 soas to force it into sealing position.

The control channel 20 (in connection with the embodiment of FIG. 4) andthe adjoining chamber 12 (in connection with the embodiment of FIGS.1-3) are herein defined as means containing a controlled pres sure meansfor control of the sealing ring 51, as herein described.

What we claim is:

l. A valve arrangement for the working cylinder of a pneumaticallyoperated tool, comprising:

a tool housing;

a working cylinder mounted in said tool housing;

a piston reciprocable in said working cylinder;

a channel formed in said housing through which com pressed air is passedto said cylinder;

at least one annular valve chamber formed in said housing operativelyadjacent said channel;

at least one elastic, radially deformable ring arranged in said channel.said at least one ring having outer rims which constitute controlpressure areas.

an auxiliary valve means for operatively controlling said controlpressure areas;

said at least one ring having inner rims constituting closing membersfor said air channel,

said housing being formed with an outlet opening communicating with theinterior of said working cylinder and formed with an annular grooveunderneath said working cylinder, said annular groove communicating withsaid outlet opening;

an additional elastic. radially deformable ring mounted underneath saidworking cylinder in said annular groove of said tool housing;

said additional elastic ring having an outer rim constituting a controlpressure surface and an inner rim serving as a closing means for saidoutlet opening;

a second channel formed in said housing and communicating with saidannular groove; and

means for communicating a means containing a controlled pressure mediuminto said second channel. said outer rim of said additional elastic ringcom- (ill said housing forms a housing bore in which said auxiliaryvalve means is operatively disposed. as well as a control channelcommunicating said housing bore with said valve chamber; and

said means for communicating comprises a tube connected to said secondchannel and communicating with said control channel and said housing.bore. constituting said means containing a controlled pressure medium.

1. A valve arrangement for the working cylinder of a pneumaticallyoperated tool, comprising: a tool housing; a working cylinder mounted insaid tool housing; a piston reciprocable in said working cylinder; achannel formed in said housing through which compressed air is passed tosaid cylinder; at least one annular valve chamber formed in said housingoperatively adjacent said channel; at least one elastic, radiallydeformable ring arranged in said channel, said at least one ring havingouter rims which constitute control pressure areas, an auxiliary valvemeans for operatively controlling said control pressure areas; said atleast one ring having inner rims constituting closing members for saidair channel, said housing being formed with an outlet openingcommunicating with the interior of said working cylinder and formed withan annular groove underneath said working cylinder, said annular groovecommunicating with said outlet opening; an additional elastic, radiallydeformable ring mounted underneath said working cylinder in said annulargroove of said tool housing; said additional elastic ring having anouter rim constituting a control pressure surface and an inner rimserving as a closing means for said outlet opening; a second channelformed in said housing and communicating with said annular groove; andmeans for communicating a means containing a controlled pressure mediuminto said second channel, said outer rim of said additional elastic ringcommunicating via said second channel with said controlled pressuremedium.
 2. A valve arrangement according to claim 1, wherein saidhousing forms an adjoining chamber adjacent said working cylinder andcommunicating therewith, said adjoining chamber constitutes said meanscontaining a controlled pressure medium; and a throttle is arranged insaid second channel.
 3. A valve arrangement according to claim 1 whereinsaid housing forms a housing bore in which said auxiliary valve means isoperatively disposed, as well as a control channel communicating saidhousing bore with said valve chamber; and said means for communicatingcomprises a tube connected to said second channel and communicating withsaid control channel and said housing bore, constituting said meanscontaining a controlled pressure medium.